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Patent 2672528 Summary

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(12) Patent: (11) CA 2672528
(54) English Title: METHOD AND APPARATUS FOR DETECTING PORT SCANS WITH FAKE SOURCE ADDRESS
(54) French Title: PROCEDE ET DISPOSITIF DE DETECTION DE BALAYAGE DE PORTS (PORT SCAN) AVEC UNE FAUSSE ADRESSE SOURCE
Status: Granted
Bibliographic Data
(51) International Patent Classification (IPC):
  • H04L 12/22 (2006.01)
  • H04L 29/06 (2006.01)
(72) Inventors :
  • KEOHANE, SUSANN MARIE (United States of America)
  • MCBREARTY, GERALD FRANCIS (United States of America)
  • MULLEN, SHAWN PATRICK (United States of America)
  • MURILLO, JESSICA CAROL (United States of America)
  • SHIEH, JOHNNY MENG-HAN (United States of America)
(73) Owners :
  • INTERNATIONAL BUSINESS MACHINES CORPORATION (United States of America)
(71) Applicants :
  • INTERNATIONAL BUSINESS MACHINES CORPORATION (United States of America)
(74) Agent: CHAN, BILL W.K.
(74) Associate agent:
(45) Issued: 2013-06-25
(86) PCT Filing Date: 2008-04-16
(87) Open to Public Inspection: 2008-10-30
Examination requested: 2011-03-16
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/EP2008/054617
(87) International Publication Number: WO2008/128941
(85) National Entry: 2009-06-12

(30) Application Priority Data:
Application No. Country/Territory Date
11/738,547 United States of America 2007-04-23

Abstracts

English Abstract

A computer implemented method, apparatus, and computer program product for port scan protection. A reply data packet having a modified transmission control protocol header is generated to form a modified reply data packet, in response to detecting a port scan. The modified reply data packet will illicit a response from a recipient of the modified data packet. The reply data packet is sent to a first Internet protocol address associated with the port scan. A second Internet protocol address is identified from a header of the response to the modified reply data packet. The second Internet protocol address is an actual Internet protocol address of a source of the port scan. All network traffic from the second Internet protocol address may be blocked to prevent an attack on any open ports from the source of the port scan.


French Abstract

Procédé, dispositif mis en AEuvre sur ordinateur et produit du type programme informatique de protection contre le balayage de ports. Selon l'invention, un paquet de données de réponse ayant un en-tête de protocole de contrôle de transmission modifié est généré pour former un paquet de données de réponse modifié en réponse à la détection d'un balayage de port. Ce paquet de données de réponse modifié rend illicite la réponse d'un destinataire du paquet de données modifié. Le paquet de données de réponse est envoyé à une première adresse de protocole Internet associée à un balayage de port. Une seconde adresse de protocole Internet est identifiée à partir d'un en-tête de la réponse au paquet de données de réponse modifié. La seconde adresse de protocole Internet est l'adresse de protocole Internet réelle de la source du balayage de ports. Tout le trafic réseau depuis la seconde adresse de protocole Internet peut être bloqué pour empêcher une attaque sur tous les ports ouverts depuis la source de balayage de ports.

Claims

Note: Claims are shown in the official language in which they were submitted.


33

1. A computer implemented method for port scan protection, the computer
implemented
method comprising:
responsive to detecting a port scan, generating, by a processor, a reply data
packet having
a modified header conforming to a protocol used to transmit data packets to
form a modified
reply data packet, wherein the modified reply data packet will elicit a
response from a recipient
of the modified reply data packet, wherein the modified header will compel the
recipient's
transmission control protocol/internet protocol layer to respond to the
modified reply data packet
in response to the recipient snooping the modified reply data packet;
sending the modified reply data packet to a first source internet protocol
address
associated with the port scan; and
responsive to receiving the response to the modified reply data packet,
identifying that a
second source internet protocol address in a header of the response is a coned
source internet
protocol address of a source of the port scan, wherein the second source
internet protocol address
is different from the first source internet protocol address.
2. The comPuter implemented method of claim 1 wherein the modified header
conforming
to the protocol includes a bad sequence number.
3. The computer implemented method of claim 2 wherein the bad sequence
number is a
protocol violation that will excite a response from the recipient.
4. The computer implemented method of claim 2 wherein the bad sequence
number is a
sequence number falling outside an acceptable range of sequence numbers.
5. The computer implemented method of claim 1 wherein the modified header
conforming
to the protocol includes a reset flag.
6. The computer implemented method of claim 1 wherein the modified header
conforming
to the protocol includes a finish flag.

34

7. The computer implemented method of claim 1 wherein modifying the header
further
comprises:
altering a checksum used to generate the modified reply data packet.
8. The computer implemented method of claim 1 further comprising:
blocking all network traffic originating from the second routing address to
prevent an
attack on any open ports.
9. The computer implemented method of claim 1 wherein the first routing
address is not a
correct routing address of a computing device.
10. The computer implemented method of claim 1 further comprising:
responsive to receiving a port scan data packet, identifying a source routing
address in a
header of the port scan data packet as the first routing address.
11. The computer implemented method of claim 1 wherein the modified header
conforming
to the protocol is a modified transmission control protocol header.
12. The computer implemented method of claim 1 wherein the modified header
conforming
to the protocol is a modified user datagram protocol header.
13. The computer implemented method of claim 1 wherein a datalink layer in
the modified
header indicates a media access control address for a destination of the
modified reply data
packet.
14. A computer program product for port scan protection, the computer
program product
comprising:
a computer usable storage device including computer usable program code
embodied
therewith, the computer usable program code comprising:

35

computer usable program code for generating a reply data packet having a
modified
header conforming to a protocol used to transmit data packets to form a
modified reply data
packet in response to detecting a port scan, wherein the modified reply data
packet will elicit a
response data packet from a recipient of the modified reply data packet,
wherein the modified
header will compel the recipient's transmission control protocol/internet
protocol layer to
respond to the modified reply data packet in response to the recipient
snooping the modified
reply data packet;
computer usable program code for sending the modified reply data packet to a
first source
internet protocol address associated with the port scan; and
computer usable program code for identifying that a second source internet
protocol
address in a header of the response data packet in response to receiving the
response data packet
a correct source internet protocol address of a source of the port scan,
wherein the second source
internet protocol address is different from the first source internet protocol
address.
15. The computer program product of claim 14 wherein the modified header
conforming to
the protocol includes a bad sequence number.
16. The computer program product of claim 15 wherein the bad sequence
number is a
sequence number falling outside an acceptable range of sequence numbers.
17. The computer implemented method of claim 15 wherein the bad sequence
number is a
protocol violation that will excite a response from a recipient of the reply
data packet.
18. The computer program product of claim 14 wherein the modified header
conforming to
the protocol includes a reset flag,
19. The computer program product of claim 14 wherein the modified header
conforming to
the protocol includes a finish flag.

36

20. The computer program product of claim 14 farther comprising:
computer usable program code for altering a checksum used to generate the
modified
reply data packet.
21. The computer program product of claim 14 further comprising:
computer usable program code for blocking all network traffic originating from
the
second routing address to prevent an attack on any open ports.
22. The computer program product of claim 14 wherein the modified header
conforming to
the protocol is a modified transmission control protocol header.
23. The computer program product of claim 14 wherein a datalink layer in
the modified
header indicates a media access control address for a destination of the
modified reply data
packet.
24. An apparatus comprising:
a bus system;
a communications system connected to the bus system;
a memory connected to the bus system, wherein the memory includes computer
usable
program code; and
a processing unit connected to the bus system, wherein the processing unit
executes the
computer usable program code to generate a reply data packet haying a modified
header
conforming to a protocol used to transmit data packets to form a modified
reply data packet in
response to detecting a port scan, wherein the modified reply data packet will
elicit a response
data packet from a recipient of the modified reply data packet, wherein the
modified header win
compel the recipient's transmission control protocol/internet protocol layer
to respond to the
modified reply data packet in response to the recipient snooping the modified
reply data packet;
send the modified reply data packet to a first source internet protocol
address associated with the
port scan; and identify that a second source internet protocol address in a
header of the response
data packet in response to receiving the response data packet a correct source
internet protocol

37

address of a source of the port scan, wherein the second source internet
protocol address is
different from the first source internet protocol address.
25. The apparatus of claim 24 wherein the modified header conforming to the
protocol
includes a bad sequence number.
26. The apparatus of claim 25 wherein the bad sequence number is a protocol
violation that
Will excite a response from a recipient of the reply data packet.
27. The apparatus of claim 24 wherein the modified header conforming to the
protocol
includes a reset flag.
28. The apparatus of claim 24 wherein the modified header conforming to the
protocol
includes a finish flag,
29. The apparatus of claim 24 wherein the processor unit further executes
the computer
usable program code to block all network traffic originating from the second
routing address to
prevent an attack on any open ports.
30. The apparatus of claim 24 wherein the modified header conforming to the
protocol is a
modified transmission control protocol header.
31. The apparatus of claim 24 wherein a datalink layer in the modified
header indicates a
media access control address for a destination of the modified reply data
packet.
32. A system for protecting against port scans, the system comprising:
a host computer, wherein the host computer comprises:
an enhanced port scan protection software for detecting a port scan data
packet and
generating a reply data packet having a modified header conforming to a
protocol used to
transmit data packets to form a modified reply data packet in response to
detecting a port scan,
wherein the modified reply data packet will elicit a response data packet from
a recipient of the

38

modified reply data packet, wherein the modified header will compel the
recipient's transmission
control protocol/internet protocol layer to respond to the modified reply data
packet in response
to the recipient snooping the modified reply data packet, wherein the modified
reply data packet
is sent to a first source internet protocol address associated with the port
scan; and
a source Internet protocol address detector, wherein the source Internet
protocol address
detector identifies that a second source interact protocol address in a header
of a response to the
modified reply data packet is a correct source internet protocol address of a
source of the port
scan, wherein the second source internet protocol address is different from
the first source
interne protocol address.
33. The system of claim 32 wherein the modified header conforming to the
protocol includes a
protocol violation that will excite the response from the recipient of the
reply data packet.
34. The system of claim 32 wherein the modified header conforming to the
protocol includes a
reset flag or a finish flag.
35. The system of claim 32 wherein the host computer is a first computer and
further comprising:
a second computer, wherein the second computer comprises:
a port scanner, wherein the port scanner performs the port scan on the first
computer by
sending the port scan data packet having a fake source routing address to the
first computer,
wherein the fake source routing address is not a correct routing address for
the second computer;
and
a transmission control protocol/Internet protocol layer, wherein the
transmission control
protocol/Internet protocol layer generates the response to the modified reply
data packet
automatically.

Description

Note: Descriptions are shown in the official language in which they were submitted.



CA 02672528 2009-06-12
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METHOD AND APPARATUS FOR DETECTING
PORT SCANS WITH FAKE SOURCE ADDRESS
BACKGROUND OF THE INVENTION
Field of the Invention

The present invention is related generally to a data processing system and in
particular to a
method and apparatus for data processing system security. More particularly,
the present
invention is directed to a computer implemented method, apparatus, and
computer usable
program code for blocking a port scanner using fake source Internet protocol
addresses.
Description of the Related Art

A user on a computing device, such as a client, connected to a network can
execute an
application or other service available on a different computing device, such
as a server, by
connecting to a port on the server associated with the application or service.
A port is an
endpoint to a logical connection between a client and a server in a network.
Ports are
typically identified by a port number. Each application available on the
server is associated
with a different port number.

In other words, a port is like a door or gateway to a particular application
on a computer.
Like a door, a port may be open or closed. An open port on a server is a port
associated with
an application that is currently available on the server for use by one or
more client
computers. A closed port is a port that is not associated with an application
or service that is
available on the server. A hacker typically cannot access a computer through a
closed port.
A computing device can access a particular application on a server by
specifying the port
number associated with the particular application. However, sometimes
unauthorized or
malicious users may want to access an application or service on the server for
purposes of
launching an attack on the server. These users are typically referred to as
hackers or


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2
computer crackers. The server that is attacked by a hacker may be referred to
as an intended
victim.

Hackers generally do not know what applications or services are available on
the intended
victim. Therefore, the hacker may perform a port scan. A port scan is a method
for
systematically scanning a computer's ports to determine which ports are open
ports
associated with an available application or service and which ports are closed
ports. In port
scanning, a series of messages are sent requesting a connection with each well-
known port.
The response received from the intended victim indicates whether the well-
known port is an
open port or a closed port. Port scanning is used by hackers to locate open
access points to a
computer which may be vulnerable to an attack.

Once a vulnerable open port is located, a hacker can launch an attack that may
cause the
resources of the application associated with the attacked open port
unavailable to intended
users of the application. This type of attack is sometimes referred to as a
denial-of-service
(DOS) attack.

One solution to this problem is provided by port scan protection software.
Current port scan
protection software identifies the source Internet protocol (IP) address in a
connection
request that may be part of a port scan. The port scan protection software
then blocks that
source IP address. In other words, the port scan software does not allow any
additional
messages from that source IP address to be received. This can prevent
subsequent attacks by
a hacker using the same source IP address.

However, hackers have circumvented current port scan prevention software by
using fake
source IP addresses during port scans to locate open ports. When the port scan
software
recognizes that a port scan may be taking place, the port scan prevention
software blocks the
fake IP address identified in the port scan messages. However, the current
port scan
prevention software does not block the hacker's actual IP address. Thus, the
hacker remains
free to launch attacks on any open ports using the hacker's actual IP address,
which is not
blocked by the port scan protection software. These attacks may lead to denial-
of-service
(DOS) effects on users attempting to gain legitimate access to applications
and/or services


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3
provided by the intended victim. In addition, these attacks can lead to loss
of time, data, and
revenue while the applications and/or services are unavailable.

SUMMARY OF THE INVENTION
The illustrative embodiments provide a computer implemented method, apparatus,
and
computer usable program code for port scan protection. In one embodiment, the
process
generates a reply data packet having a modified header for a protocol used to
transmit data
packets to form a modified reply data packet in response to detecting a port
scan. In one
embodiment, the modified header for a protocol used to transmit data packets
is a modified
transmission control protocol header.

The modified reply data packet will illicit a response from a recipient of the
modified data
packet. The process sends the reply data packet to a first routing address
associated with the
port scan.

The process identifies a second routing address in a header of the response
data packet in
response to receiving a response to the modified reply data packet. The second
routing
address is an actual routing address of a source of the port scan. All network
traffic from the
second routing address may then be blocked to prevent an attack on any open
ports. In one
embodiment, the first routing address is a first Internet protocol address and
the second
routing address is a second Internet protocol address.

The modified header for the protocol used to transmit data packets may include
a bad
sequence number. A bad sequence number is a sequence number falling outside an
acceptable range of sequence numbers or a protocol that elicits a response
from the recipient
of the reply data packet. In another embodiment, the modified header may
include a reset
flag or a finish flag. In another embodiment, the modified header is generated
by altering a
checksum used to generate the modified reply data packet.
Viewed from a first aspect, the present invention provides a method for port
scan protection,
the method comprising the steps o responsive to detecting a port scan,
generating a reply


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data packet having a modified header for a protocol used to transmit data
packets to form a
modified reply data packet, wherein the modified reply data packet obtains a
response from a
recipient of the modified reply data packet; sending the modified reply data
packet to a first
routing address associated with the port scan; and responsive to receiving the
response to the
modified reply data packet, identifying a second routing address in a header
of the response,
wherein the second routing address is an actual routing address of a source of
the port scan.
Preferably, the present invention provides a method wherein the modified
header for the
protocol comprises a sequence number which falls outside an acceptable range
of sequence
numbers.

Preferably, the present invention provides a method wherein the sequence
number is a
protocol violation that will obtain a response from the recipient.

Preferably, the present invention provides a method wherein the modified
header for the
protocol comprises a reset flag.

Preferably, the present invention provides a method wherein the modified
header for the
protocol comprises a finish flag.
Preferably, the present invention provides a method wherein modifying the
header further
comprises: altering a checksum used to generate the modified reply data
packet.

Preferably, the present invention provides a method further comprising the
step o blocking
network traffic originating from the second routing address to prevent an
attack on any open
ports.

Preferably, the present invention provides a method wherein the first routing
address is not a
correct routing address of a computing device.


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Preferably, the present invention provides a method further comprising the
step o
responsive to receiving a port scan data packet, identifying a source routing
address in a
header of the port scan data packet as the first routing address.

5 Preferably, the present invention provides a method wherein the modified
header for the
protocol is a modified transmission control protocol header.

Preferably, the present invention provides a method wherein the modified
header for the
protocol is a modified user datagram protocol header.
Preferably, the present invention provides a method wherein the first routing
address is a
first Internet protocol address and wherein the second routing address is a
second Internet
protocol address.

Viewed from a second aspect, the present invention provides an apparatus
comprising: a bus
system; a communications system connected to the bus system; a memory
connected to the
bus system, wherein the memory comprises a computer usable program code; and a
processing unit connected to the bus system, wherein the processing unit
executes the
computer usable program code to generate a reply data packet having a modified
header for
a protocol used to transmit data packets to form a modified reply data packet
in response to
detecting a port scan, wherein the modified reply data packet obtains a
response data packet
from a recipient of the modified reply data packet; sends the modified reply
data packet to a
first routing address associated with the port scan; and identifies a second
routing address in
a header of the response data packet in response to receiving the response
data packet,
wherein the second routing address is an actual routing address of a source of
the port scan.
Preferably, the present invention provides an apparatus wherein the modified
header for the
protocol comprises a sequence number, wherein the sequence number is a
sequence number
which falls outside a range of acceptable sequence numbers. .
Preferably, the present invention provides an apparatus wherein the modified
header for the
protocol comprises a reset flag.


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Preferably, the present invention provides an apparatus wherein the modified
header for the
protocol comprises a finish flag.

Preferably, the present invention provides an apparatus wherein the processor
unit further
executes the computer usable program code to block all network traffic
originating from the
second routing address to prevent an attack on any open ports.

Preferably, the present invention provides an apparatus wherein the sequence
number is a
protocol violation that obtains a response from a recipient of the reply data
packet.
Preferably, the present invention provides an apparatus wherein the modified
header for the
protocol is a modified transmission control protocol header.

Preferably, the present invention provides an apparatus wherein the first
routing address is a
first Internet protocol address and wherein the second routing address is a
second Internet
protocol address.

Viewed from a third aspect, the present invention provides a system for
protecting against
port scans, the system comprising: a host computer, wherein the host computer
comprises:
an enhanced port scan protection software for detecting a port scan data
packet and
generating a reply data packet having a modified header for a protocol used to
transmit data
packets to form a modified reply data packet in response to detecting a port
scan; and a
source Internet protocol address detector, wherein the source Internet
protocol address
detector identifies a source routing address in a header of a response to the
modified reply
data packet, wherein the source routing address is an actual routing address
of a source of the
port scan.

Preferably, the present invention provides a system wherein the modified
header for the
protocol comprises a protocol violation for triggering a response from a
recipient of the reply
data packet.


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Preferably, the present invention provides a system wherein the modified
header for the
protocol comprises a reset flag or a finish flag.

Preferably, the present invention provides a system wherein the host computer
is a first
computer and further comprising: a second computer, wherein the second
computer
comprises: a port scanner, wherein the port scanner performs the port scan on
the first
computer by sending the port scan data packet having a fake source routing
address to the
first computer, wherein the fake source routing address is not a correct
routing address for
the second computer; and a transmission control protocoUInternet protocol
layer, wherein
the transmission control protocoUInternet protocol layer generates the
response to the
modified reply data packet automatically.

Viewed from a fourth aspect, the present invention provides a computer program
product
loadable into the internal memory of a digital computer, comprising software
code portions
for performing, when said product is run on a computer, to carry out all the
steps of the
method described above.

Viewed from a fifth aspect computer program product comprising: a computer
usable
medium including computer usable program code for port scan protection, said
computer
program product comprising: computer usable program code for generating a
reply data
packet having a modified header for a protocol used to transmit data packets
to form a
modified reply data packet in response to detecting a port scan, wherein the
modified reply
data packet will illicit a response data packet from a recipient of the
modified reply data
packet; computer usable program code for sending the modified reply data
packet to a first
routing address associated with the port scan; and computer usable program
code for
identifying a second routing address in a header of the response data packet
in response to
receiving the response data packet, wherein the second routing address is an
actual routing
address of a source of the port scan.

Preferably, the present invention provides a computer program product wherein
the modified
header for the protocol comprises a sequence number.


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Preferably, the present invention provides a computer program wherein the
sequence number
is a sequence number falling outside an acceptable range of sequence numbers.

Preferably, the present invention provides a computer implemented method
wherein the
sequence number is a protocol violation that will obtain a response from a
recipient of the
reply data packet.

Preferably, the present invention provides a computer program product wherein
the modified
header for the protocol comprises a reset flag.
Preferably, the present invention provides a computer program product wherein
the modified
header for the protocol comprises a finish flag.

BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention are described below in detail, by way of example
only, with
reference to the accompanying drawings in which:

Figure 1 is a pictorial representation of a network of data processing systems
in which
preferred embodiments of the present invention may be implemented;

Figure 2 is a block diagram of a data processing system in which preferred
embodiments of
the present invention may be implemented;

Figure 3 is a block diagram of an open systems interconnection (OSI) basic
reference model
in accordance with a preferred embodiment of the present invention;

Figure 4 is a block diagram illustrating a currently used port scan protection
mechanism;
Figure 5 is a block diagram illustrating a flow through a port scan protection
system for
detecting a port scan with a fake source IP address in accordance with a
preferred
embodiment of the present invention;


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Figure 6 is a block diagram illustrating a port scan protection mechanism in
accordance with
a preferred embodiment of the present invention;

Figure 7 is an exemplary illustration of port scan packets transmitted during
a port scan in
accordance with a preferred embodiment of the present invention;

Figure 8 is a flowchart illustrating a process for detecting a port scan with
a fake source IP
address in accordance with a preferred embodiment of the present invention;
and

Figure 9 is a flowchart illustrating a process for modifying a reply data
packet in accordance
with a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference now to the figures and in particular with reference to Figures
1-2, exemplary
diagrams of data processing environments are provided in which illustrative
embodiments
may be implemented. It should be appreciated that Figures 1-2 are only
exemplary and are
not intended to assert or imply any limitation with regard to the environments
in which
different embodiments may be implemented. Many modifications to the depicted
environments may be made.

With reference now to the figures, Figure 1 depicts a pictorial representation
of a network of
data processing systems in which illustrative embodiments may be implemented.
Network
data processing system 100 is a network of computers in which embodiments may
be
implemented. Network data processing system 100 contains network 102, which is
the
medium used to provide communications links between various devices and
computers
connected together within network data processing system 100. Network 102 may
include
connections, such as wire, wireless communication links, or fiber optic
cables.

In the depicted example, server 104 and server 106 connect to network 102
along with
storage unit 108. In addition, clients 110, 112, and 114 connect to network
102. These
clients 110, 112, and 114 may be, for example, personal computers or network
computers.


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In the depicted example, server 104 provides data, such as boot files,
operating system
images, and applications to clients 110, 112, and 114. Clients 110, 112, and
114 are clients
to server 104 in this example. Network data processing system 100 may include
additional
servers, clients, and other devices not shown.
5
A computing device, such as client 110, can execute an application or other
service available
on a different computing device, such as server 106, available over network
102 by
connecting to a port on server 106 associated with the desired application or
service. An
application is computer software that uses the resources of a computing device
to perform a
10 task or service for a user.

A port is an endpoint to a logical connection between client 110 and server
106 in network
102. Ports are typically identified by a port number. Port numbers range from
0 to 65,536.
Port numbers are assigned by the Internet Assigned Numbers Authority (IANA).
The
Internet Assigned Numbers Authority is operated by Internet Corporation for
Assigned
Names and Numbers (ICANN).

Each application available on server 104 or 106 is associated with a different
port number.
Some port numbers are pre-assigned based on the type of application or service
that is
associated with a given port. These pre-assigned or standard port numbers are
referred to as
well-known ports. There are approximately 1,024 well-known port numbers
reserved or pre-
assigned to particular services and applications. For example, well-known port
numbers
include, but are not limited to, port 80 for hypertext transfer protocol
(HTTP) traffic, port 23
for Telnet, port 25 for simple mail transfer protocol (SMTP), port 53 for
domain name

servers (DNS), and port 194 for Internet relay chat (IRC). Thus, any port on
any server that
is designated for hypertext transfer protocol traffic will typically have an
assigned port
number of 80.

Client 110 can access a particular application on server 104 or 106 by sending
a connection
request that specifies the port number associated with the particular
application.


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11
In the depicted example, network data processing system 100 is the Internet
with network
102 representing a worldwide collection of networks and gateways that use the
Transmission
Control ProtocoUInternet Protocol (TCP/IP) suite of protocols to communicate
with one
another. At the heart of the Internet is a backbone of high-speed data
communication lines
between major nodes or host computers, consisting of thousands of commercial,
governmental, educational and other computer systems that route data and
messages. Of
course, network data processing system 100 also may be implemented as a number
of
different types of networks, such as for example, an intranet, a local area
network (LAN), or
a wide area network (WAN). Figure 1 is intended as an example, and not as an
architectural
limitation for different embodiments.

With reference now to Figure 2, a block diagram of a data processing system is
shown in
which illustrative embodiments may be implemented. Data processing system 200
is an
example of a computer, such as server 106 or client 110 in Figure 1, in which
computer
usable code or instructions implementing the processes may be located for the
illustrative
embodiments.

In the depicted example, data processing system 200 employs a hub architecture
including a
north bridge and memory controller hub (MCH) 202 and a south bridge and
input/output
(I/O) controller hub (ICH) 204. Processing unit 206, main memory 208, and
graphics
processor 210 are coupled to north bridge and memory controller hub 202.
Processing unit
206 may contain one or more processors and even may be implemented using one
or more
heterogeneous processor systems. Graphics processor 210 may be coupled to the
MCH
through an accelerated graphics port (AGP), for example.
In the depicted example, local area network (LAN) adapter 212 is coupled to
south bridge
and I/O controller hub 204 and audio adapter 216, keyboard and mouse adapter
220, modem
222, read only memory (ROM) 224, universal serial bus (USB) ports and other
communications ports 232, and PCI/PCIe devices 234 are coupled to south bridge
and I/O
controller hub 204 through bus 238, and hard disk drive (HDD) 226 and CD-ROM
drive 230
are coupled to south bridge and I/O controller hub 204 through bus 240.
PCI/PCIe devices
may include, for example, Ethernet adapters, add-in cards, and PC cards for
notebook


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12
computers. PCI uses a card bus controller, while PCIe does not. ROM 224 may
be, for
example, a flash binary input/output system (BIOS). Hard disk drive 226 and CD-
ROM
drive 230 may use, for example, an integrated drive electronics (IDE) or
serial advanced
technology attachment (SATA) interface. A super I/O (SIO) device 236 may be
coupled to
south bridge and I/O controller hub 204.

An operating system runs on processing unit 206 and coordinates and provides
control of
various components within data processing system 200 in Figure 2. The
operating system
may be a commercially available operating system such as Microsoft Windows XP
(Microsoft and Windows are trademarks of Microsoft Corporation in the United
States, other
countries, or both). An object oriented programming system, such as the JavaTM
programming system, may run in conjunction with the operating system and
provides calls
to the operating system from Java programs or applications executing on data
processing
system 200. Java and all Java-based trademarks are trademarks of Sun
Microsystems, Inc. in
the United States, other countries, or both.

Instructions for the operating system, the object-oriented programming system,
and
applications or programs are located on storage devices, such as hard disk
drive 226, and
may be loaded into main memory 208 for execution by processing unit 206. The
processes
of the illustrative embodiments may be performed by processing unit 206 using
computer
implemented instructions, which may be located in a memory such as, for
example, main
memory 208, read only memory 224, or in one or more peripheral devices.

The hardware in Figures 1-2 may vary depending on the implementation. Other
internal
hardware or peripheral devices, such as flash memory, equivalent non-volatile
memory, or
optical disk drives and the like, may be used in addition to or in place of
the hardware
depicted in Figures 1-2. Also, the processes of the illustrative embodiments
may be applied
to a multiprocessor data processing system.

In some illustrative examples, data processing system 200 may be a personal
digital assistant
(PDA), which is generally configured with flash memory to provide non-volatile
memory for
storing operating system files and/or user-generated data. A bus system may be
comprised


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13
of one or more buses, such as a system bus, an I/O bus and a PCI bus. Of
course the bus
system may be implemented using any type of communications fabric or
architecture that
provides for a transfer of data between different components or devices
attached to the fabric
or architecture. A communications unit may include one or more devices used to
transmit
and receive data, such as a modem or a network adapter. A memory may be, for
example,
main memory 208 or a cache such as found in north bridge and memory controller
hub 202.
A processing unit may include one or more processors or CPUs. The depicted
examples in
Figures 1-2 and above-described examples are not meant to imply architectural
limitations.
For example, data processing system 200 also may be a tablet computer, laptop
computer, or
telephone device in addition to taking the form of a PDA.

Transmission control protocoUInternet protocol (TCP/IP) is a suite of
communications
protocols used to connect computing devices over a network, such as network
102 in Figure
1. Transmission control protocol and Internet protocol are the standard
protocols for
transmitting data over networks, such as the Internet.

Turning now to Figure 3, a block diagram of an open systems interconnection
(OSI) basic
reference model is shown in accordance with an illustrative embodiment. Open
systems
interconnection reference mode1300 is a common model of standard protocol
layers for
defining interoperability and communications between network devices. In this
example,
open systems interconnection reference mode1300 includes the transmission
control
protocoUInternet protocol (TCP/IP) suite.

TCP/IP and similar protocols are utilized by open systems interconnection
communications
architecture. In this example, the architecture includes application layer
302, presentation
layer 304, session layer 306, transport layer 308, network layer 310, datalink
layer 312, and
physical layer 314. Each layer is responsible for handling various functions
and/or
communications tasks.

Application layer 302 handles the details of the particular application being
accessed and/or
executed. Many common TCP/IP applications are present for almost every
implementation,


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14
including a Telnet for remote login; a file transfer protocol (FTP); a simple
mail transfer
protocol (SMTP) for electronic mail; and a simple network management protocol
(SNMP).
The application software handled by application layer 302 may include any
number of
software applications designed to react to data through the communications
port to provide
the desired functionality the user seeks. Applications at this level may
include those
necessary to handle data, video, graphics, photos, and/or text which can be
accessed by users
of the Internet.

Presentation layer 304 includes a presentation protocol and a presentation
service. The
presentation service is used to identify an agreed upon transfer syntax that
will be used. The
presentation protocol enables users to communicate with the presentation
service.

Session layer 306 consists of a session protocol and a session service. The
session service
provides services to the user, including, but not limited to, establishing
connections between
session-service users, terminating connections between users, performing
negotiations for
use of session layer tokens, and synchronizing points in transmitted data to
permit the
session to be recovered if an error or interruption occurs. The session
protocol allows users
to communicate with the session service.
Next, transport layer 308 provides an interface between network layer 310 and
application
layer 302 that facilitates the transfer of data between two host computers.
Transport layer
308 is concerned with things such as, but not limited to, dividing the data
passed to it from
the application into appropriately sized chunks for the network layer below,
acknowledging
received packets, and setting timeouts to make certain the other end
acknowledges packets
that are sent. In the TCP/IP protocol suite, two distinctly different
transport protocols are
present, transmission control protocol (TCP) and user datagram protocol (UDP).
Transmission control protocol provides reliability services to ensure that
data is properly
transmitted between two hosts, including dropout detection and retransmission
services.
Conversely, user datagram protocol provides a much simpler service to
application layer 302
by merely sending relatively simple packets of data called datagrams from one
host to the


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other. Datagrams are transmitted without providing any mechanism for
guaranteeing that
the data in the datagram is properly transferred. When using user datagram
protocol,
application layer 302 must perform the reliability functionality. An example
of transport
layer data packet information includes, but is not limited to, a port number
for a source host
5 and/or a port number for a destination host.

Network layer 310, which may also be referred to as the Internet layer,
handles the
movement of packets of data around the network. For example, network layer 310
handles
the routing of various packets of data that are transferred over the network.
Network layer
10 310 in the TCP/IP suite is comprised of several protocols, including
Internet protocol (IP),
Internet control message protocol (ICMP), and Internet group management
protocol (IGMP).
Internet protocol (IP) may include, but is not limited to, Internet protocol
version 4 (IPv4),
Internet protocol version 6 (IPv6), or any other known or available version of
Internet
protocol. An example of network layer data packet information may include, but
is not
15 limited to, an Internet protocol (IP) address identifying a source host IP
address and/or a
destination host IP address.

Datalink layer 312 may also be referred to as the link layer or the network
interface layer and
normally includes the device driver in the operating system and the
corresponding network
interface card in the computer. Datalink layer 312 typically handles all the
hardware details
of physically interfacing with physical layer 314, such as, but not limited
to, an Ethernet
network Interface card and/or a wireless Internet adapter. An example of
datalink layer data
packet information may include, but is not limited to, a media access control
(MAC) address.

Physical layer 314 refers to the network media being used, such as optical
cables or Ethernet
cables. In other words, physical layer 314 is the physical network cable
connecting a
computing device, such as client 110 in Figure 1, to a network, such as
network 102 in
Figure 1.

The mechanism of the illustrative embodiments may be more specifically
implemented in a
layer, such as transport layer 308 and/or network layer 310.


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Figure 4 is a block diagram illustrating a currently used port scan protection
mechanism.
Network data processing system 400 is a data processing system including two
or more
computing devices connected to a network, such as network data processing
system 100 in
Figure 1. In this example, the network is the Internet. However, the network
may also
include a local area network, a wide area network, an Ethernet, or any other
type of network.
Network data processing system 400 includes malicious host 402 and victim 404.

Malicious host 402 is a hacker or other unauthorized user on a computing
device, such as
client 110 in Figure 1, performing a port scan of victim 404. In other words,
malicious host
402 is attempting to locate a vulnerable open access point in victim 404 so
that malicious
host 402 can gain unauthorized access to victim 404 and/or launch an attack on
victim 404
through the open port. Malicious host 402 is performing a port scan of victim
404 to locate
vulnerable open access points for use in launching an attack against victim
404.

Victim 404 is a computing device hosting one or more applications and/or
services.
Malicious Host 402 is connected to a network, such as network 102 in Figure 1.
A client
computing device can access the applications and/or services available on
victim 404 by
requesting a connection to a port associated with a given application or
service through a
network connection.
Victim 404 includes port scan protection 405. Port scan protection 405 is any
currently
available port scan protection software for detecting port scans and blocking
a source IP
address of malicious host 402. A common method by which port scan protection
405 works
is by monitoring a set of closed ports which are not being used by victim 404,
but may be
used by hackers for exploitation due to vulnerabilities associated with the
applications
associated with the ports. Port scan protection 405 assumes that legitimate
users would not
attempt to access a port in the set of closed ports because legitimate users
would know that
victim 404 does not provide the applications or services associated with the
set of closed
ports. Only malicious hosts, such as malicious host 402 would attempt to
connect to a port
in the set of closed ports because they are fishing for vulnerable services
listening on the
ports.


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If port scan protection 405 detects a data packet requesting a connection to a
port in the set
of closed ports, such as a synchronization (SYN) data packet or a pattern of
these data
packets coming from a particular remote host, port scan protection 405 will
shun or block all
traffic from the particular remote host. In this manner, even if the remote
host detected a
vulnerable open port, the remote host will not be able to launch an attack
because all future
network traffic from the remote host is blocked.

In this example, malicious host 402 performs a port scan by sending a series
of data packets
to victim 404 requesting a connection to one or more well-known ports on
victim 404. Data
packet 406 is one of the series of data packets sent by malicious host 402.

Data packet 406 is a transmission control protocoUInternet protocol (TCP/IP)
data packet
containing a request to connect to a port identified as port "n" on victim
404. In this
example, data packet 406 is transmission control protocol synchronization (TCP
SYN)
message requesting connection to port "n." Port "n" may be any port number,
such as port
80 associated with hypertext transfer protocol traffic.

In this example, data packet 406 includes a fake or false source IP address. A
source IP
address is an IP address identifying the sender of a data packet. A fake
source IP address is
an IP address identifying incidental victim 408 rather than the actual sender
of data packet
406. Incidental victim 408 may be an actual computing device or incidental
victim 408 may
not actually exist. In other words, the fake IP address used by malicious host
402 does not
have to identify an actual computing device. In this example, data packet 406
includes
source IP address "A" associated with incidental victim 408 rather than IP
address "B"
which is the actual IP address for malicious host 402.

In response to receiving data packet 406, victim 404 sends data packet 410 to
incidental
victim 408. Data packet 410 is a transmission control protocoUInternet
protocol data packet
indicating whether port "x" is an open port or a closed port. In this example,
data packet 410
is a synchronize acknowledge (SYN/ACK) message. Data packet 410 is being sent
to a
destination IP address "A" associated with incidental victim 408. Therefore,
malicious host


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402 will not receive data packet 410 in the ordinary course of message
transmission from
victim 404 to incidental victim 408.

Because malicious host 402 is not the intended recipient of data packet 410,
malicious host
402 snoops 412 data packet 410 from the network. Snooping refers to capturing
or viewing
a data packet that was intended to be sent to a different destination
computing device. In this
example, malicious host 402 uses a packet sniffer to snoop data packet 410
intended to be
received by incidental victim 408. A packet sniffer is an application that
captures data
packets transmitted over the network despite the fact that the malicious host
is not the
intended recipient of the data packet.

Thus, malicious host 402 is informed as to whether port "x" is an open port
that may be
vulnerable to attack. If port "x" is an open port, malicious host 4021aunches
attack 414
against victim 404.
Victim 404 has current port scan protection software. The current port scan
protection
allows victim 404 to recognize data packet 406 as a possible port scan from a
hacker, such as
malicious host 402. The current port scan protection software enables victim
404 to block
subsequent messages from the source IP address identified in a suspected port
scan, such as
data packet 406. However, because the source IP address in data packet 406 was
a fake IP
address, victim 404 will not block messages from malicious host 402, such as
messages from
malicious host 402 associated with attack 414. In this manner, malicious host
402 may be
able to bypass current port scan protection software to attack and possibly
disable or
compromise victim 404.
Thus, in this example, malicious host 402 is a port scanner that is attempting
to connect to a
vulnerable port by sending a TCP SYN packet, such as data packet 406, to a
given port on
victim 404. Data packet 406 generated by malicious host 402 includes a fake
source IP
address for an incidental victim that may or may not exist. If there is a
program or
application listening on the given port, victim 404 responds by sending a TCP
SYN/ACK
packet, such as data packet 410 to the incidental victim.


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Malicious host 402 monitors the network and sees data packet 410 go by.
Malicious host
402 determines that the given port is an open port that can be connected to
for exploitation of
any existing vulnerabilities in the application associated with the given
port. Malicious host
402 can determine which application is associated with the given port based on
the well-
known port numbers assigned to each port.

Port scan protection 405 on victim 404 responds to the fake packet by blocking
the fake
source IP address "A" for incidental victim 408. Malicious host 402 is free to
send attack
414 to the given port on victim 404 using the appropriate hacking tool for
this particular port
and vulnerable application program associated with the particular port.

The illustrative embodiments recognize that when current port scan protection
software
responds to a fake data packet using a fake source IP address received from a
hacker during
a port scan, the port scan protection software responds by blocking the fake
source IP
address for the incidental victim, rather than the actual IP address for the
true malicious host.
The current port scan protection software fails to identify and block the true
source IP
address where fake source IP addresses are provided by a malicious host.
Therefore, the
illustrative embodiments recognize the need for enhanced port scan protection
software that
will shun a host IP address that is actually launching an attack as quickly as
possible after a
port scan is detected.

Thus, the illustrative embodiments provide a computer implemented method,
apparatus, and
computer usable program code for port scan protection. In one embodiment, the
process
generates a reply data packet having a modified header for a protocol used to
transmit data
packets to form a modified reply data packet in response to detecting a port
scan.

In the illustrative embodiments described below, the modified header for the
protocol that is
used to transmit data packets is a modified transmission control protocol
header. However,
the illustrative embodiments are not limited to modifying headers in
transmission control
protocols. The illustrative embodiments may modify a header in any type of
known or
available protocol used for transmitting data packets over a network
connection to form a


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modified reply data packet, including, but not limited to, transmission
control protocol or
user datagram protocol (UDP).

The modified reply data packet will illicit a response from a recipient of the
modified data
5 packet. The process sends the reply data packet to a first routing address
associated with the
port scan. The process identifies a second routing address in a header of the
response data
packet in response to receiving a response to the modified reply data packet.
In the
examples described below, the first routing address is a first Internet
protocol address and
the second routing address is a second Internet protocol address. The Internet
protocol may
10 be any version of Internet protocol, including but not limited to, Internet
protocol version 4
(IPv4), Internet protocol version 6 (IPv6), or any other version of Internet
protocol. In
addition, the illustrative embodiments are not limited to Internet protocol.
Any type of
known or available protocol for providing routing addresses for one or more
ports may be
used in accordance with the illustrative embodiments.
The second routing address is an actual routing address of a source of the
port scan. All
network traffic from the second routing address may then be blocked to prevent
an attack on
any open ports.

Turning now to Figure 5, a block diagram illustrating a flow through a port
scan protection
system for detecting a port scan with a fake source IP address is shown in
accordance with
an illustrative embodiment. Computer 500 may be implemented using any type of
computing device, including but not limited to, server 106 or client 110 in
Figure 1.

Computer 500 includes set of applications 502. Set of applications 502 is a
set of one or
more applications and/or services available on computer 500. An application is
computer
software that uses the resources of a computing device to perform a task or
service for a
user.

Set of applications 502 may be stored on a data storage device, such as data
storage device
504. Data storage device 504 is any type of known or available device for
storing data,
including but not limited to, main memory, a database, a read only memory
(ROM), a


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random access memory (RAM), a non-volatile random access memory (NV-RAM), a
hard
disk, a flash memory, a floppy disk, a compact disk rewritable (CD-RW), or any
other type
of data storage device. In this example, data storage device 504 is located on
or locally to
computer 500. However, data storage device 504 may also be located remotely to
computer
500.

Computer 500 uses transmission control protocoUInternet protocol (TCP/IP) 506
to transmit
and receive messages from other computing devices connected to a network, such
as
network 102 in Figure 1. TCP/IP 506 is a suite of standard protocols for
providing a
connection between a sender and receiver. TCP/IP 506 may provide guaranteed
delivery
and ensure that packages are received in a correct sequence. In other words,
when messages
are sent from another computing device to computer 500, the messages may not
be received
in order. Therefore, TCP/IP 506 uses transmission control protocol (TCP)
sequence
numbers to ensure the messages are delivered to the application layer in the
correct order.
TCP/IP 506 gives a sequence number to every message that is sent by TCP/IP 506
so that a
recipient of the messages can determine the correct order for the messages.
Initial sequence
numbers (ISNs) are exchanged between computer 500 and a second computing
device when
the connection between computer 500 and the second computing device is
established.
TCP/IP 506 allows for receiving messages with sequence numbers that are out of
sequence if
the out-of-sequence numbers are within certain bounds or limitations. However,
if the
sequence number is too far outside the expected range of sequence numbers, the
message
will be disregarded or identified as a bad message. In such cases, computer
500 may request
the second computer resend the message with the bad sequence number.
TCP/IP 506 includes port 508 and port 510. In this example, computer 500 is
depicted as
having two ports. However, computer 500 may have any number of ports.

Port 508 has an assigned port number and is associated with an application in
set of
applications 502. For example, if port 508 is associated with an application
for handling
hypertext transfer protocol traffic, then port 508 would be assigned to port
number 80. In
this example, port 508 is an open port.


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Port 510 is also assigned a port number. In this example, port 510 is assigned
port number
20 for file transfer protocol (FTP). However, in this example, file transfer
protocol is not
available on computer 500. Therefore, port 510 is a closed port.

Computer 500 also includes enhanced port scan protection 512. Enhanced port
scan
protection 512 is port scan protection software for detecting port scans and
blocking an IP
address associated with a malicious host or other computing device performing
the port scan,
such as malicious host 516.

Malicious host 516 is a hacker, cracker, unauthorized user, or illegitimate
user performing a
port scan on one or more ports associated with computer 500, such as ports 508
and 510.
Malicious host 516 includes TCP/IP 518 suite of protocols for sending and
receiving data
packets over the network. Malicious host 516 connects to computer 500 over
this network
connection.
Malicious host 516 includes port scanner 520. Port scanner 520 may be any type
of known
or available device for performing a port scan of a set of one or more ports
on computer 500.
Port scanner 520 may be implemented completely in software or as a combination
of
hardware and software. In this example, port scanner 520 generates port scan
data packet
522. Port scan data packet 522 comprises fake source IP address 524. Fake
source IP
address 524 is not an IP address associated with malicious host 516. Fake
source IP address
524 may be an IP address for an actual computing device other than malicious
host 516, or
fake source IP address 524 may be an IP address for a computing device that
does not
actually exist.
Enhanced port scan protection 512 includes source IP address detection 514.
Source IP
address detection 514 is a software component for generating reply data packet
526. Reply
data packet 526 is a data packet that is modified to compel TCP/IP 518 on
malicious host
516 to generate response 528. In other words, if enhanced port scan detection
512 detects a
port scan, enhanced port scan protection 512 responds by sending reply data
packet 526 to
malicious host 516 that will cause malicious host 516 to send response 528.
Response 528
may include a reset (RST) flag or finish acknowledge (FIN/ACK) flag in the
transmission


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control protocol header of response 528. In this example, response 528 also
includes the
malicious host's real IP address 530 in the network layer of the transmission
control protocol
header of response 528.

Computer 500 can identify the malicious host's real IP address 530 from
response 528.
Enhanced port scan protection 512 then shuns or blocks real IP address 530 of
malicious
host 516 to prevent any future attacks from malicious host 516.

Next, Figure 6 is a block diagram illustrating a port scan protection
mechanism in
accordance with an illustrative embodiment. Network data processing system 600
is a data
processing system including multiple computing devices connected over a
network, such as
network data processing system 100 in Figure 1. In this example, the network
is the
Internet. However, the network may also include a local area network, a wide
area network,
an Ethernet, or any other type of network. Network data processing system 600
includes
malicious host 602 and victim 604.

Malicious host 602 is a hacker or other unauthorized user on a computing
device, such as
client 110 in Figure 1, or malicious host 516 in Figure 5. Malicious host 602
is performing
an unauthorized port scan on victim 604 in an attempt to locate a vulnerable
open access
point so that malicious host 602 can gain unauthorized access to victim 604
and/or launch an
attack on victim 604 through the open port.

Victim 604 is a computing device hosting one or more applications and/or
services, such as
server 106 in Figure 1 or computer 500 in Figure 5. A client computing device
can access
the applications and/or services available on victim 604 by requesting a
connection to a port
associated with a given application or service through a network connection.

Victim 604 includes enhanced port scan protection 605 that includes source IP
address
detection software, such as enhanced port scan protection 512 in Figure 5.
Enhanced port
scan protection 605 is software for use in identifying an IP address of
malicious host 602
when malicious host 6021aunches a port scan by sending data packet 606 using a
fake


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source IP address and blocking the IP address for malicious host 602 rather
than blocking the
fake source IP address used by malicious host 602.

Malicious host 602 performs a port scan by sending a series of data packets to
victim 604
requesting a connection to one or more well-known ports on victim 604. Data
packet 606 is
one of the series of data packets sent by malicious host 602 to a port on
victim 604, such as
port scan data packet 522 in Figure 5.

Data packet 606 is a transmission control protocoUInternet protocol data
packet requesting a
connection to a port identified as port "n" on victim 604. In this example,
data packet 606 is
a transmission control protocol synchronization (TCP SYN) data packet. Port
"n" may be
any port number, such as port 80 associated with hypertext transfer protocol
traffic.

Data packet 606 includes a fake or false source IP address for an incidental
victim. The
incidental victim may or may not actually exist. In this example, data packet
606 includes
source IP address "A" associated with an incidental victim, rather than IP
address "B" which
is the actual IP address for malicious host 602.

In response to receiving data packet 606, enhanced port scan protection 605
generates data
packet 608. Data packet 608 is a reply data packet, such as reply data packet
526 in Figure
5. Data packet 608 is manufactured so that the data packet will illicit a
response from
malicious host 602 if malicious host 602 snoops data packet 608 from off the
network. The
header of the transmission control protocol (TCP) header of data packet 608 is
altered in a
manner that will trick the TCP/IP layer of the malicious host into responding
to data packet
608 if malicious host 602 snoops data packet 608 from the network.

For example, if enhanced port scan protection 605 gives data packet 608 a bad
sequence
number, TCP/IP layer of malicious host 602 will respond by sending a
synchronization
(SYN) flag in an attempt to reconnect to victim 604. A bad sequence number is
a sequence
number that is outside the expected or acceptable range of possible sequence
numbers.


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A finish (FIN) flag indicates the end of a session. When a data packet,
including a finish
flag, is received, TCP/IP automatically sends a finish acknowledgement in
response. Thus,
if port scan protection 605 gives data packet 608 a finish flag, TCP/IP layer
of malicious
host 602 will automatically send a finish acknowledge (FIN/ACK) flag in a
response
5 message to victim 604.

Thus, in this example, enhanced port scan protection 605 sends data packet 608
to the
incidental victim associated with the fake source IP address. Data packet 608
is a
transmission control protocoUInternet protocol data packet indicating whether
port "n" is an
10 open port or a closed port. In this example, data packet 608 contains a
synchronize
acknowledge (SYN/ACK) flag and a bad sequence number. Victim 604 sends data
packet
608 to the fake IP address "A" associated with the incidental victim.

The datalink layer in the header of data packet 608 indicates a media access
control (MAC)
15 address for the destination of data packet 608. The media access control
address specifies
the particular network adapter of the destination computing device. In this
case, the media
access control address specifies the network adapter of the incidental victim.

Normally, if malicious host 602 was not running in snoop mode, malicious host
602 would
20 not receive data packet 608 because the datalink layer media access control
address does not
match the network adapter associated with malicious host 602. However, in this
example,
malicious host 602 is in snoop mode. Therefore, the Ethernet driver associated
with
malicious host 602 will ignore the media access control address in the header
of data packet
608 and pass data packet 608 up the TCP/IP layer associated with malicious
host 602.
Malicious host 602 snoops data packet 608 from the network. In this example,
malicious
host 602 uses a packet sniffer to snoop data packet 608 from the network. In
response to
detecting the bad sequence number in data packet 608, the TCP/IP layer of
malicious host
602 automatically generates and transmits a response to data packet 610 to
victim 604 in an
attempt to reconnect to victim 604. Data packet 610 is a response data packet,
such as
response 528 in Figure 5.


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26
Data packet 610 contains the actual source IP address "B" for malicious host
602 rather than
the fake IP address "A." Enhanced port scan protection 605 blocks the actual
source IP
address "B" from sending further messages to victim 604 over the network. In
this manner,
malicious host 602 is blocked from launching any attacks on any vulnerable
ports on victim
604.

Figure 7 is an exemplary illustration of port scan packets transmitted during
a port scan in
accordance with an illustrative embodiment. Port scan data packet 702 is a
data packet
having a false source IP address generated by a malicious host, such as port
scan data packet
522 in Figure 5 and/or data packet 606 in Figure 6. In this example, the port
scan data
packet is a synchronization (SYN) data packet.

Reply data packet 703 is a data packet generated by a recipient of port scan
data packet 702,
such as reply data packet 526 in Figure 5 and/or data packet 608 in Figure 6.
The recipient
is an intended victim of the malicious host. Reply data packet 703 is
generated by the victim
and sent to the false IP address. In this example, the reply data packet is a
synchronization
acknowledge (SYN/ACK) data packet generated by an intended victim of the
malicious host,
such as victim 604 in Figure 6.

Port scan data packet 702 includes information for the datalink layer in
section 704. The
transmission route of the port scan data packet from the malicious host to the
intended victim
will assign the Ethernet (ETH) media access control (MAC) address based on
routing tables.
Port scan data packet 702 also includes information in the network layer. The
network layer
information includes a fake source IP address "A" in line 705. The fake source
IP address
"A" is an IP address for an existent or non-existent incidental victim, rather
than the actual
IP address for the malicious host that generated port scan data packet 702.
The network
layer information in the data packet also includes a destination IP address
706 identifying the
victim computing device.
The transport layer information in port scan data packet 702 identifies a
source port number
for the malicious hacker and a destination port number for the victim host
computing device,


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27
as shown in line 708. Line 710 is a sequence number for the port scan packet.
Line 712
identifies the data packet as a synchronization (SYN) data packet requesting a
connection
with the victim computing device.

Reply data packet 703 includes a source IP address for victim 714 and
destination IP address
716. Destination IP address 716 is the fake IP address used by the malicious
hacker.

The transport layer information includes a source port number for the victim
computing
device generating the reply data packet, as shown in line 714. Line 716
includes a
destination IP address. The destination IP address in this example is the fake
IP address for
the incidental victim. The incidental victim may or may not actually exist.

Line 722 may provide a bad sequence number. The bad sequence number is a
sequence
number that is outside the expected or acceptable range of possible sequence
numbers.
Line 722 indicates that reply data packet 703 is a synchronization/acknowledge
(SYN/ACK)
data packet. In another example, line 722 could indicate that reply data
packet 703 is a reset
(RST) or finish (FIN) data packet.

In other words, using currently available port scan protection software, if
the victim had an
active service on port 23, which may be identified in line 708, the victim
would respond by
generating a SYN/ACK reply data packet. This would be the end of the session
between
port 23 on the victim and port 1494 of the malicious host. The malicious host
would then
know that the victim had a telnet service running on port 23. The malicious
host could then
launch a telnet attack on port 23. The current port scan protection software
would block the
fake IP address identified in line 705 of the port scan packet but would be
unable to block
the actual IP address of the malicious host. Thus, the malicious host would be
free to attack
port 23.

In accordance with the illustrative embodiments, when the victim receives port
scan data
packet 702, the enhanced port scan protection software on the victim responds
in such a way
as to obligate the actual malicious host to respond. For example, the enhanced
port scan


CA 02672528 2009-06-12
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28
protection software generates reply data packet 703 that includes a bad
sequence number, a
reset (RST) message, or a finish (FIN) message. Because the incidental host
never sent port
scan data packet 702, the incidental host will not respond to reply data
packet 703. Instead,
if the incidental host actually exists, the incidental host will only ignore
reply data packet
703. If the incidental host does not exist, then the incidental host cannot
respond to reply
data packet 703. Thus, only the malicious host is expected to respond to reply
data packet
703. In this manner, the victim can identify and block the actual IP address
of a malicious
host using a port scan to identify open ports that may be vulnerable to attack
by the
malicious host.
Referring now to Figure 8, a flowchart illustrating a process for detecting a
port scan with a
fake source IP address is depicted in accordance with an illustrative
embodiment. In this
illustrative example shown in Figure 8, the process is performed by a software
component
for port scan protection, such as enhanced port scan protection 512 in Figure
5.
The process begins by making a determination as to whether a port scan is
detected (step
802). If a port scan is not detected, the process returns to step 802 until a
port scan is
detected. A port scan may be detected when a port scan data packet or a series
of data
packets is received from a malicious host.
If a port scan is detected in step 802, the process generates a modified reply
data packet (step
804). The process sends the modified reply data packet to the source IP
address identified in
the port scan data packet (step 806). In this example, the source IP address
is a fake source
IP address that is not a correct IP address of the host conducting the port
scan.
The process then makes a determination as to whether a response to the reply
is received
(step 808). If a response is not received, the process returns to step 808
until a response is
received. When a response is received in step 808, the process blocks all
network traffic
from a second IP address identified in the transmission control protocol
header of the
response (step 810) to prevent any attacks that may be launched from the
source of the port
scan with the process terminating thereafter.


CA 02672528 2009-06-12
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29
Figure 9 is a flowchart illustrating a process for modifying a reply data
packet in accordance
with an illustrative embodiment. In this example in Figure 9, the process may
be
implemented by a software component for port scan protection, such as enhanced
port scan
protection 512 in Figure 5.
The process begins by generating a reply data packet (step 902). The process
makes a
determination as to whether to modify the reply data packet by adding a bad
sequence
number to the transmission control protocol header for the reply data packet
(step 904). If a
determination is made to modify the reply data packet by adding a bad sequence
number, the
process adds a bad sequence number to the header of the reply data packet
(step 906) and
transmits the modified reply data packet to the incidental victim (step 908)
with the process
terminating thereafter.

Returning to step 904, if a determination is made that a bad number sequence
will not be
added, the process makes a determination as to whether to add a reset flag or
a finish flag to
the reply data packet (step 910). If the process makes a determination that a
flag will not be
added, the process terminates thereafter.

Returning to step 910, if the process makes a determination to modify the
reply data packet
by adding a reset flag or a finish flag, the process adds a reset flag or a
finish flag (step 912)
to the reply data packet. The process then sends the modified reply data
packet to the
incidental victim (step 908) with the process terminating thereafter.

Thus, the illustrative embodiments provide a computer implemented method,
apparatus, and
computer usable program code for port scan protection. In one embodiment, the
process
generates a reply data packet having a modified transmission control protocol
header to form
a modified reply data packet in response to detecting a port scan. The
modified reply data
packet will illicit a response from a recipient of the modified data packet.
The process sends
the reply data packet to a first Internet protocol address associated with the
port scan.
The process identifies a second Internet protocol address in a header of the
response data
packet in response to receiving a response to the modified reply data packet.
The second


CA 02672528 2009-06-12
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Internet protocol address is an actual Internet protocol address of a source
of the port scan.
All network traffic from the second Internet protocol address may then be
blocked to prevent
an attack on any open ports.

5 The modified transmission control protocol header may include a bad sequence
number. A
bad sequence number is a sequence number falling outside an acceptable range
of sequence
numbers. In another embodiment, the modified transmission control protocol
header may
include a reset flag or a finish flag. In another embodiment, the modified
transmission
control protocol is generated by altering a checksum used to generate the
modified reply data
10 packet.

In this manner, attacks on open and potentially vulnerable ports by hackers
using false IP
addresses can be prevented.

15 The flowchart and block diagrams in the figures illustrate the
architecture, functionality, and
operation of possible implementations of systems, methods and computer program
products
according to various embodiments. In this regard, each step in the flowchart
or block
diagrams may represent a module, segment, or portion of code, which comprises
one or
more executable instructions for implementing the specified logical
function(s). It should
20 also be noted that, in some alternative implementations, the functions
noted in the steps may
occur out of the order noted in the figures. For example, two steps shown in
succession
may, in fact, be executed substantially concurrently, or the steps may
sometimes be executed
in the reverse order, depending upon the functionality involved.

25 The invention can take the form of an entirely hardware embodiment, an
entirely software
embodiment or an embodiment containing both hardware and software elements. In
a
preferred embodiment, the invention is implemented in software, which includes
but is not
limited to firmware, resident software, microcode, etc.

30 Furthermore, the invention can take the form of a computer program product
accessible from
a computer-usable or computer-readable medium providing program code for use
by or in
connection with a computer or any instruction execution system. For the
purposes of this


CA 02672528 2009-06-12
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31
description, a computer-usable or computer readable medium can be any tangible
apparatus
that can contain, store, communicate, propagate, or transport the program for
use by or in
connection with the instruction execution system, apparatus, or device.

The medium can be an electronic, magnetic, optical, electromagnetic, infrared,
or
semiconductor system (or apparatus or device) or a propagation medium.
Examples of a
computer-readable medium include a semiconductor or solid state memory,
magnetic tape, a
removable computer diskette, a random access memory (RAM), a read-only memory
(ROM), a rigid magnetic disk and an optical disk. Current examples of optical
disks include

compact disk - read only memory (CD-ROM), compact disk - read/write (CD-R/W)
and
DVD.

A data processing system suitable for storing and/or executing program code
will include at
least one processor coupled directly or indirectly to memory elements through
a system bus.
The memory elements can include local memory employed during actual execution
of the
program code, bulk storage, and cache memories which provide temporary storage
of at least
some program code in order to reduce the number of times code must be
retrieved from bulk
storage during execution.

Input/output or I/O devices (including but not limited to keyboards, displays,
pointing
devices, etc.) can be coupled to the system either directly or through
intervening I/O
controllers.

Network adapters may also be coupled to the system to enable the data
processing system to
become coupled to other data processing systems or remote printers or storage
devices
through intervening private or public networks. Modems, cable modem and
Ethernet cards
are just a few of the currently available types of network adapters.

The description of the present invention has been presented for purposes of
illustration and
description, and is not intended to be exhaustive or limited to the invention
in the form
disclosed. Many modifications and variations will be apparent to those of
ordinary skill in
the art. The embodiment was chosen and described in order to best explain the
principles of


CA 02672528 2009-06-12
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32
the invention, the practical application, and to enable others of ordinary
skill in the art to
understand the invention for various embodiments with various modifications as
are suited
to the particular use contemplated.

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Administrative Status

Title Date
Forecasted Issue Date 2013-06-25
(86) PCT Filing Date 2008-04-16
(87) PCT Publication Date 2008-10-30
(85) National Entry 2009-06-12
Examination Requested 2011-03-16
(45) Issued 2013-06-25

Abandonment History

There is no abandonment history.

Maintenance Fee

Last Payment of $624.00 was received on 2024-03-20


 Upcoming maintenance fee amounts

Description Date Amount
Next Payment if standard fee 2025-04-16 $624.00
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Please refer to the CIPO Patent Fees web page to see all current fee amounts.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Application Fee $400.00 2009-06-12
Maintenance Fee - Application - New Act 2 2010-04-16 $100.00 2009-06-12
Request for Examination $800.00 2011-03-16
Maintenance Fee - Application - New Act 3 2011-04-18 $100.00 2011-04-01
Maintenance Fee - Application - New Act 4 2012-04-16 $100.00 2012-01-09
Maintenance Fee - Application - New Act 5 2013-04-16 $200.00 2013-03-22
Final Fee $300.00 2013-04-15
Maintenance Fee - Patent - New Act 6 2014-04-16 $200.00 2014-03-21
Maintenance Fee - Patent - New Act 7 2015-04-16 $200.00 2015-03-31
Maintenance Fee - Patent - New Act 8 2016-04-18 $200.00 2016-03-29
Maintenance Fee - Patent - New Act 9 2017-04-18 $200.00 2017-03-21
Maintenance Fee - Patent - New Act 10 2018-04-16 $250.00 2018-03-20
Maintenance Fee - Patent - New Act 11 2019-04-16 $250.00 2019-03-26
Maintenance Fee - Patent - New Act 12 2020-04-16 $250.00 2020-04-01
Maintenance Fee - Patent - New Act 13 2021-04-16 $255.00 2021-03-23
Maintenance Fee - Patent - New Act 14 2022-04-19 $254.49 2022-03-23
Maintenance Fee - Patent - New Act 15 2023-04-17 $473.65 2023-03-21
Maintenance Fee - Patent - New Act 16 2024-04-16 $624.00 2024-03-20
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
INTERNATIONAL BUSINESS MACHINES CORPORATION
Past Owners on Record
KEOHANE, SUSANN MARIE
MCBREARTY, GERALD FRANCIS
MULLEN, SHAWN PATRICK
MURILLO, JESSICA CAROL
SHIEH, JOHNNY MENG-HAN
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Abstract 2009-06-12 2 78
Claims 2009-06-12 4 149
Drawings 2009-06-12 6 109
Description 2009-06-12 32 1,555
Representative Drawing 2009-06-12 1 12
Cover Page 2009-09-24 2 48
Claims 2012-12-19 6 237
Representative Drawing 2013-06-07 1 8
Cover Page 2013-06-07 1 46
PCT 2009-06-12 2 59
Assignment 2009-06-12 3 122
Correspondence 2010-04-30 1 15
Correspondence 2010-06-14 1 12
Correspondence 2010-05-14 2 50
Prosecution-Amendment 2011-03-16 1 23
Prosecution-Amendment 2012-06-19 4 124
Prosecution-Amendment 2012-12-19 9 352
Correspondence 2013-04-15 1 28